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Picked up a charcoal canister. While cleaning it up I checked the airflow of each port. All clear except the Dist Vac port that comes out of the cap that says Do Not Remove Cap. But I opened it in order to see if it was clogged. It appears to me that this particular port is not designed for air flow either direction. I conclude this only because it enters into a sealed area of the cap. I've seen a diagram in the TSM showing an arrow flow coming from the canister to the carb. Attaching many images from the TSM and the canister.

Question: what purpose is this port of it is truly sealed with no flow to our from the canister?

Ported vacuum operates a valve that controls the rate of purge through the primary purge connection. More volume of purge is allowed off-idle.

Got it. Ok, makes sense. This is an 82 Cherokee, inline 6, with a MC 2100 carb.

Is this increased volume of purge off-idle more efficient such that I should put it back to it's original configuration?

Prior owner removed canister and I was initially only looking to plug in the vapor carb bowl line, then I learned there are 4 ports, so if new configuration created more efficiency then I'd like to achieve less stress on engine and better fuel efficiency.

I don't understand what you are asking.

Purge comes from the primary purge. It acts like a vacuum leak, adding air to the mixture. I would assume that the canister is designed so its added air is ok under all throttle conditions. Will it purge sufficiently with the valve always closed (ie always at the idle volume)? I don't know - seems unlikely.

I assume the two inlets are just that, two inlets differing only in nipple size and labeling. On my '82, the bowl vent has a solenoid valve that closes when the key is on. You need the vapor separator, solenoid valve, and air cleaner door to make it work properly. The bowl is always open to the vents in the air horn. When the engine is off, the air cleaner door closes, the bowl vent opens and the bowl can only vent through the canister.

I thought I knew what I was asking but I didn't. I meant to ask about the secondary purge line coming from the canister. I am wondering why the connection to the canister of the secondary purge line is sealed inside. I assumed from your description that it was maybe offering just a little extra purge somehow through the line even though there is no air flow beyond what's in the length of the connecting line.

It just operates the valve - it does not connect to the inside of the canister. All the purge - large or small volume - goes through the primary purge connection.

You understand about ported vacuum? zero at idle.

Thanks. I had to do some reading on line to understand ported vacuum. Can't say I understand it fully but I'm now aware of how the canister works which keeps me going on installing it.

Ported vacuum comes from a port in the carburetor. This port is blocked by the throttle flap at idle. Thus zero vacuum at idle. Otherwise the same as manifold vacuum.

As stated above on ported vacuum port, the ported nipple on carb will pull no vacuum at idle, but as soon as you step on the gas to go vacuum is now there on that port, and whatever is connected to it.
So, ported vacuum allows the engine to run at idle only using base mechanical timing, then when carb engaged to drive the vehicle, activating that line to pull vacuum to whatever is connected to it. Most times that will be the vacuum advance on the distributor.

Manifold vacuum will be always there, as long as the engine is running.
So if this is connected to the vacuum advance on the distributor, it will be running with base timing + whatever vacuum advance on distributor is pulling, even at idle.

Hope this helps.